A common arrangement of tension and chain stopper device for vessel anchoring chains is shown in FIG. 1. This comprises a fairlead 21 attached to the side of the vessel 22 close to a bottom 23 of the vessel 22. It also comprises a chain stopper 24 arranged at a deck 25 level of the vessel. A chain 31 extends from a seabed anchor (not shown) through the fairlead 21 and to the chain stopper 24. The arrangement also comprises a chain adjusting device 26, which in turn comprises a trolley 27 that is moveable on tracks 28. A chain winch 33 is placed in the trolley 27. Next to the trolley 27 is a chain container 30 for storing non-active pull chain.
The system comprises a plurality of fairleads 21 and chain stoppers 24. The trolley 27 is moveable between the chain stoppers 24 to tighten or slacken the chains according to needs. When a chain is to be, e.g., tightened, the trolley 27 will be brought to the chain stopper 24 holding this chain, a pull chain 22 stored in the chain container (there is one pull chain for each mooring chain) is fed over a turn down wheel 29 and connected to the mooring chain 31. Then the anchor winch 29 is activated, the chain stopper 24 released and the anchor chain 31 is pulled to the required tension.
This process has to be repeated as the anchor chain slackens due to stretching of the chain, wear of the chain, displacement of the anchor of because the vessel has to be moved short distances without the need to change the anchor positions. The multiple chains (typically, the vessel is moored by 5 or 6 chains arranged at 4 separate locations, such as one location at each side of the bow and one location at each side of the stern) should have substantially the same tension.